This invention pertains generally to mass spectrometry. This invention pertains particularly to a method employing mass spectrometry to generate correlative data from various products of thermal degradation of biological specimens so as to facilitate their classification and their identification.
Prior methods employing mass spectrometry to generate correlative data concerning biological specimens are discussed in two significant published references:
(1) H. L. C. Meuzelaar et al., "A Technique for Fast and Reproducible Fingerprinting of Bacteria by Pyrolysis Mass Spectrometry," Analytical Chemistry, Vol. 45, No. 3, March 1973, pages 587 et seq.;
(2) John P. Anhalt et al., "Identification of Bacteria Using Mass Spectrometry,"Analytical Chemistry, Vol. 47, No. 2, February 1975, pages 219 et seq.,
Also in:
(3) Henry L. Friedman et al.; a paper presented to the American Chemical Society, Second Western Regional Meetings, October 16-19, 1966 as summarized in Chemical & Engineering News, Sept. 5, 1966, Thermochimica Acta 1 (1970), pages 199 et seq. at 223-224; and Thermal Analysis, 1, (1969), pages 405 et seq. at 408-409.
Prior applications of mass spectrometry to other studies of related interest are discussed in three additional published references:
(4) Everett K. Gibson, Jr., et al., "Thermogravimetric-Quadrupole Mass-Spectrometric Analysis of Geochemical Samples," Thermochimica Acta, 4, (1972) pages 49 et seq.;
(5) Everett K. Gibson, Jr., "Thermal Analysis-Mass Spectrometer Computer System and its Application to the Evolved Gas Analysis of Green River Shale and Lunar Soil Samples," Thermochimica Acta, 5, (1973), pages 243 et seq.; and
(6) Alfred L. Yergey et al., "Nonisothermal Kinetics Studies of the Hydrodesulfurization of Coal," Industrial & Engineering Chemistry, Process Design & Development, VOl. 13, July 1974, pages 233 et seq.
As described generally in references (1) and (2), prior methods to generate correlative data concerning bacterial specimens reflect such steps employing mass spectrometry for each specimen as degrading such specimen by heating such specimen so as to cause various products of thermal degradation of such specimen to be evolved, ionizing such products, detecting ion currents corresponding to different ratios of mass-to-charge among such products, and recording such detected ion currents. Referenct (2) describes a methodology wherein each specimen contained in a melting point capillary tube was introduced into a heated ion source operated at 300.degree.-350.degree. C. Reference (1) describes a methodology wherein ferromagnetic wires of Curie points of 510.degree. C were used to heat a specimen. Reference (3) discloses unsatisfactory results, which are evident from the summary in Thermal Analysis.
Reference (1) suggests, at page 590, that ionization techniques causing negligible fragmentation such as field ionization, chemical ionization, or low-voltage electron-impact ionization may be useful. Further reference may be made to U.S. Pat. No. 3,555,272, which describes chemical ionization in substantial detail.
Reference (4) and reference (5) commonly disclose mass spectrometry as applied to monitor and identify released gases, whose spectra are known, from individual samples of geochemical substances. Reference (6) discloses kenetic studies of hydrogen sulfide, whose spectra are known, as evolved from non-isothermally heated coal.
Herein, the term "correlative" means susceptible to cross-correlation by known manual and automated techniques.